Telethermoscope



H. W. AND H. HARDINGE.

TELETHERMOSCOPE. Mmc/111011 F11ED 111311.19, 1915.

@wv @View ETD EOSCOPE lpplication nled april 19, 1916.

To @ZZ rw/lom if may concern.'

Be `it known that we, HanniNon and Hfiiniown HARDINGE, both citizens or" the United States, residing1 at blew Ycrlr, in the county and State oi New York, have invented certain new and useful linprovements in rlleletheiinoscopes, of which the following is a full, clear, and exact description.

rl`his invention' relates to teletherinoscopes, for indicating at a distant point an abnormal or sudden rise of temperature, such as would be caused by fire in the room in which the device is located, and its object is to provide an improved device for the purpose which will not deteriorate with time and which will operate with certainty when occasion arises. To this and other ends the invention consists in the novel features and combinations hereinafter described.

'lhree convenient and etective forms ci the invention are illustrated in the accompanying drawings, in which Figure l shows an embodiment in which the temperatureresponsive devices are nested one inside the other, making a device ci compact torni. lEig. 2 illustrates an embodiment in which the two bulbs or chambers are arranged side by side, and Fig. 3 shows another Jcrni.

ln lig. 1 two air-tight bulbs or chambers l0, 1l, preferably made of glass, are sealed one inside the other, as shown, but conimunicate through a small curved tube l2 at the bottom. Both these bulbs contain or other gas. 'llie inner bulb is inclosed also in an intermediate bulb 13 to prevent rapid transfer or heat from the outer bulb, and for this purpose the intermediate bulb can be iilled with heat-insulatinl material, or, preferably, may have the air exhausted Jroin it so as to leave a partial vacuum. Si small tube lil, extending through the wall ci the outer bulb, serves as convenient means through which the air can be pumped out or the insulating material introduced.

Sealed in a neck at the top of the inner bulb l0 isa pair oi separated terminals or contacts l5, 16, which extend down into the inner orilice of the tube l2. @n the outside the contacts are connected by wires 1'?, 18, through a source ot current i9 to a suit able signaling device, as a bell 20. Sealed in a neck at the outer end ci tube l2 is another pair oit insulated terminals o*y contacts, 2l, 22, connected to the bel Specification or" Letters Eatent.

un j 1 J ,i i atented le:

erial llo. 92,3%.

in' parallel with contacts l5, it, by means wires 23, 2l. it will be understoodthat the bell or other signal is located at any desired point, remote or near. ln the tube l2 is a movable contact (a sniall body ci' mercurv 25) which also serves normally to close tube against iiow ci air from one bulb into the other,

The operation of the system will now be readily understood. fi quick and abnormal rise oi' temperature, such as would be occasioned by tire, causes immediate heating of the outer bulb and the air therein but does not affect the air iii the inner bulb to the same extent, if at all, since the latter bulb is insulated by the interniediatu bulb. Hence differential expansion oiC the two bodies of air in the two bulbs occurs, the air in the outer expanding` inore than that in the inner, with the result that the body ci niercury 25 is carried up into the lett leg` of tube 12H, iniinersing the lower ends ot contacts lo, lli, thereby closing the circuit and ringing the bell Q0. iis the in the outer bulb continues to expand, the mercury is driven higher and liiier, until the aiit escapes past it into the inner bulb. The sustaining pressure being thus relieved the mercury drops bach into the bottoni oi the "tube or passage l2, thereby brealiiw y n a circuit through the bell and causing tl e lat- .L n c ier to cease ringing. The air in, the outer bulb now expands further, again driving the mercury up into the inner' bulb, as before, and the cycle described is repeated quiclr intervals as long as the rapid rise of temperature continues. li"ix.ill.fm the pressure in the inner bulb inay become too great to permit the mercury to reach the contacts, in which case the device would ceese to operate. To prevent this result a sniall vent tube 2, closed with a plug ot :net-al` wan, or other material which will inelt at asuitabl high temperature, is sealed in the upper neck. rl'hen when this t'fupeiaturc i reached the accumulated pressure in the inner bulb will blow the plug` out. therebv relieving the pressure and permitting the device to operate again as long as the teniperature continues to increase,

'lli obviate the necessity o' driving the nicrcuiy clear up into the inner bulb to pei'- IiiiiL the lifting pressure oi' 'the uli' in the outer bulli to be relieved. u tine will' oi' in liet' tube il' may be provided. lending l'rou the inner bulb down to the tube or paw CIR .and the device at'times may not 12 and communicating with the latter at a ipoint below lits orice. This tube is of too ne a bore for the mercury to enter it,l and hence as vsoon as the bottom of the column `of mercury rises above the lower end of the relieftube wthe air is by-passed through the latter into the inner bulb and the mercury then drops back below the relief tube orifice, thereby cutting 'off communication between the outer and inner bulbs 11 and 10 respectively. Further heating of the outer bulb thenehdrives the mercury up again with the same result, the operation continuing as long as the rapid rise of temperature keeps u pUnder normal conditions the rise of temperature resulting from the operation of the heating system of the building is slow. Before the air in the outer bulb can expand .with sufhcient force to lift the mercury up to the contacts 15, 16, the air in the inner bulb will be heated enough to counteract the outer pressure.

The provision of contacts 21, 22 enables the device to indicate abnormal fall of tempera'ture. Thus a sudden dron of temperature will affect the outer bulb without appreciable influence on the insulated inner bulb, with the result that the pressure in the latter exceeds the pressure in the former.

The mercury 25 is thereby driven upintothe right leg of the tube or passage 12, thus bridging the contacts 21, 22 and ringing the bell 20. When the bottom of the mercury rises above the lower orifice of the relief tube 28, the bore of which is too finey for the mercury to enter, the pressure in the inner v bulb is relieved, more or less, by iio'w of air through the relief tube, and the mercury falls back. In this way the bell is sounded intermittently, as in the case of abnormally rapid rise of temperature. The relief tube 28 is not essential, but it is desirable, particularly in a device which does not have falling temperature contacts 21, 22. It has been bserved that the body of mercury somet es sticks or clings in the upper part of the' right leg of the passage 0r tube 12.

If the contacts 21, 22 are provided, they areV thus closed and a signal given, summoning an attendant, who can put matters right; but without these contacts no si nal is given he so quickly responsive to sudden tem erature change as it is ordinarily. But wlth the relief tube present the pressure below the mercury is relived and the mercuryimmediately drops bac In either case, the escape of air past the mercury and into the inner bulb equalizes the pressures in the two bulbs, or at least reduces the pressure in the outer bulb and increases the pressure in the inner to such an extent that the former is no longer sufficient tc hold the mercury up. The latter therefore falls, exposing the vco'i'itacts and y to its high surface tension, will prevent the mercury from entering the vent tube when driven up the tube 12. The vent tube is necessarily exaggerated in siz'e in the drawn the form shown in Fig. 2 the two airtight bulbs 10a and 11a (theformer inclosed in an insulating bulb 13a) are arranged side by side instead of one inside the other. They are connected at the bottom by a tube or passage 12a containing a body of ,mercury 25, and may have relief tubes 27a, 28a, and a vent tube 26'r1 'sealed with fusible material. High temperature contacts 15a, 16a are shown inthe insulated bulb, and low temperature contacts, not shown, may be provided in bulb 11a. `In operation the device il? of course similar to that illustrated in aving the bulbs sealed air-tight is an advantageous feature, since it minimizes oxidation of the mercury. Oxidation can be eliminated or made inappreciable by havinor che buns fined withV an inert gas instead @i air, as for example, carbon dioxid, or with gas havin a reducing tendency, as for instance, car on monoxid.

If the bulb containing the high temperature contacts is larger than the other, like bulbs 10by and 11b, in Fig. 3,- the former need not be insulated; though insulation is an advantage, especially in making the device operate longer whenonce started." In this form of the device the temperature rise in than in the -large bulb, du'e to the smaller Hence the pressure per unit area (say the cross sectional area of the tube or passa e 12b, containing the .mercury 25") may he greater in the small bulb than in the larger.

In each of the devices illustrated, pres- Sure equilibrium between the two bulbs can be restored at any time by inverting the device so that the mercury will run into one of the bulbs.

It is to be understood that the invention is not limited to the devices herein specifically illustrated, but can be embodied in other forms without departure from its spirit.

We claim:

1. Tn a device of the kind described, a pair of as-filled chambers, one being heatinsulate, an electrical contact freely movable between the chambers, a pair of fixed kvolume of air (or other gas) in the former.

epafated contacts 'to be electrically closed by the movable Contact in its travel toward one of the chambers, and a by-pass for permitting the escape of gas *from one chamber to the other when 'tbe movable Contact reaches a predetermined point in its travel after closing said xed contacts, whereby rapid change of temperature will cause repeated closing of the xed contacts.

2. n a devioe of the kind described, a pair of sealed gas-lled chambers having a passage connecting the same at the bottom, one of the chambers being beat-insulated, a pair of separated contacts, a freely movable contact in the passage, normallT out of engagement with the said contacts and normally sealing the passage, and a reliez? passage extending from the first-mentioned passage belov,7 an orioe thereof and opening into the adiaoent chamber.

a o' .lied deseribed, pair of gas-iilled chamber-is, one being liestinsnlated and provided with a vent sealed with fusible material adapted to melt and permit escape or" gas a predetermined temperature above the normal, an eleetrical Contact freely movable between the chambers, a pair of xed separated contacts ar ranged to be electrically closed by the movable Contact in its travel toward one of the chambers, and a 'oy-pass `for permitting the escape of gas from one chamber to the other when the movable contact reaches a predetermined point in its travel after closing said ized contacts, whereby rapid changes of temperature will cause repeated closing of tlie xed contacts.

ln testimony whereof We hereunto affix our signatures.

HARRY HABDINGE.

HRDXNGE 

